
Comments under my post about people being more empathetic toward white people with a racist phase than the Black people affected by it
"When an ex-racist has nowhere to go they go back to racism" so you proved that they never changed, then??

"When an ex-racist has nowhere to go they go back to racism" so you proved that they never changed, then??
Hi. I'm a 24BF living in London. I wanted to ask for advice and what I can do regarding making a formal complaint against my new contract manager at work. I'm not sure if it falls under discrimination, or if it would just be classed as a standard grievance. I work in the railway industry for context. I have been working this job for 1 year and around 7 months.
Before our new contract began with a new company, our rota and the jobs people did were already fair, and there was a set system in place. That system was not broken or in need of fixing and no one had any complaints about it. I was supposed to get a slight promotion to do a different job, whilst someone else was supposed to cover for me when I would have my days off. I worked hard to earn that position and went out of my way to volunteer for other things to help the company like going to other sites to help out, where I was even made team leader.
Recently, when our new manager came, he changed this system completely which has caused problems with the everyone. He mostly only interacts with one operative and he is showing what looks like bias and favouritism toward this employee, practically allowing them to do whatever they please and get their way, whilst the rest of us are told to just "follow the rota".
He had that employee trained on the job I was supposed to be "promoted" for, and then claimed he wanted to make the system fair by taking away my opportunity to do it full-time as I was supposed to and had earned, and has now given it to that employee more than myself, essentially making me the cover instead, even though that employee never did it before or showed interest in it. As the weeks have gone on, with each rota released, I noticed that he keeps putting that operative on it for more and more days than even me, despite claiming that he wanted the system to be fair and didn't allow me to do it full time, to which i have to keep bringing up to him and reminding him. It is starting to seem like I am being lied to by someone who is supposed to be our manager in favour of someone he has deemed his favourite, especially as he keeps making excuses as to why he is letting them do it more, and seems to give them more days to punish me everytime I ask about it.
The other operatives have also noticed this favouritism and bias toward that employee that he expresses and have deemed it unfair, especially when he spends a lot of time talking to them but doesn't take the time to get to know the rest of us, and can be quite combative and argumentative to any complaints being made instead of acting in a professional manner like a manager should. I have already brought it up with him multiple times that I have noticed him taking me off of the job I was supposed to do in favour of an employee he's being biased toward. He said in a briefing that everyone should feel free to air any grievances or suggestions, but when they do, he either shuts it down quickly, takes it personally, or worse. He claimed two operatives known amongst us for speaking out are "ruining things for everyone else" which is not how a manager who claims that everyone should be allowed to speak out should say. He also accused everyone of essentially being racist for calling out his favouritism and bias toward this one operative (whom we never had a problem with before he came and changed things) by claiming we all hate people from their country which is entirely untrue, accusatory, and completely unprofessional and inappropriate. (For extra context, a majority of us are minorities whilst he and his favourite operative are white.)
Recently, I had given him two weeks notice for a 2-3 days grievance period for a family member who passed away recently, and emailed him twice about it, as well as booking it twice through the employee portal. He ignored the first email sent two weeks prior and the second email sent a few days ago, asking for an update. I messaged him about it on WhatsApp, to which he stated that he never saw the requests, yet the system shows that the request wasn't approved the first time despite him being the only one to approve holidays to my knowledge, which shows that he did see them in the system. My second request still says it is pending approval. I have seen other operatives have their holiday approved a single week prior to requesting it, including the operative he is showing favouritsm too, yet he claims to have not seen mine in the system and somehow missed my two emails. I feel as though it is highly unprofessional to be lied to so blatantly by a manager.
We all are starting to see his favouritism and bias toward this operative, and it is starting to look like discrimination (based on the fact that he seems to be happy to talk with and give good jobs to the other few white people we have, but the rest of us are brushed off and argued with and labelled troublemakers) Other operatives are also witnesses to this behaviour, and don't believe he is being fair or professional or that he is suited for the job if he continues this behaviour. It is not fair that some operatives have worked hard to get to certain positions and that it was taken away from them when this new manager and contract came in. His behaviour is starting to seem like textbook discrimination despite his gaslighting that we are imagining it.
I have already drafted an email to the HR department, but I didn't know if I should air it as a discriminatory grievance or a standard one. Would there be any bad repercussions for it?
Thank you for any help you can provide.